Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria.
Unit of Biochemistry, Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland.
Nucleic Acids Res. 2022 Sep 23;50(17):10053-10077. doi: 10.1093/nar/gkac724.
Eukaryotic ribosome synthesis involves more than 200 assembly factors, which promote ribosomal RNA (rRNA) processing, modification and folding, and assembly of ribosomal proteins. The formation and maturation of the earliest pre-60S particles requires structural remodeling by the Npa1 complex, but is otherwise still poorly understood. Here, we introduce Rbp95 (Ycr016w), a constituent of early pre-60S particles, as a novel ribosome assembly factor. We show that Rbp95 is both genetically and physically linked to most Npa1 complex members and to ribosomal protein Rpl3. We demonstrate that Rbp95 is an RNA-binding protein containing two independent RNA-interacting domains. In vivo, Rbp95 associates with helix H95 in the 3' region of the 25S rRNA, in close proximity to the binding sites of Npa1 and Rpl3. Additionally, Rbp95 interacts with several snoRNAs. The absence of Rbp95 results in alterations in the protein composition of early pre-60S particles. Moreover, combined mutation of Rbp95 and Npa1 complex members leads to a delay in the maturation of early pre-60S particles. We propose that Rbp95 acts together with the Npa1 complex during early pre-60S maturation, potentially by promoting pre-rRNA folding events within pre-60S particles.
真核生物核糖体合成涉及 200 多种组装因子，这些因子促进核糖体 RNA(rRNA) 的加工、修饰和折叠，以及核糖体蛋白的组装。最早的 pre-60S 颗粒的形成和成熟需要 Npa1 复合物的结构重塑，但目前对此仍知之甚少。在这里，我们介绍 Rbp95(Ycr016w)，一种早期 pre-60S 颗粒的组成部分，作为一种新的核糖体组装因子。我们表明，Rbp95 在遗传和物理上都与大多数 Npa1 复合物成员和核糖体蛋白 Rpl3 相关联。我们证明 Rbp95 是一种 RNA 结合蛋白，包含两个独立的 RNA 相互作用结构域。在体内，Rbp95 与 25S rRNA 的 3' 区域中的 H95 螺旋结合，靠近 Npa1 和 Rpl3 的结合位点。此外，Rbp95 还与几个 snoRNA 相互作用。Rbp95 的缺失导致早期 pre-60S 颗粒中蛋白质组成的改变。此外，Rbp95 和 Npa1 复合物成员的联合突变导致早期 pre-60S 颗粒成熟的延迟。我们提出，Rbp95 在早期 pre-60S 成熟过程中与 Npa1 复合物一起发挥作用，可能通过促进 pre-rRNA 在 pre-60S 颗粒内的折叠事件。
